Raising doubts about the veracity of the phone-hacking account given by Murdoch before the Commons Culture, Media and Sport Committee, his former employees have said they had informed him of a critical piece of evidence in the scandal.
Murdoch, who was quizzed this week, had told the committee that he was not "aware" of an email suggesting the practice went wider than a "rogue" News of the World reporter.
But former NOTW editor Colin Myler and ex-News International legal manager Tom Crone last night said they "did inform" him of the email.
In a statement issued by News Corporation, Murdoch responded by saying: "I stand by my testimony to the select committee".
The testimony in question refers to the April 2008 payment authorised by Murdoch as part of an out-of-court settlement of more than 600,000 pounds to Gordon Taylor, chief executive of the Professional Footballers' Association, over the hacking of his phone.
He said at that time he did not know the full extent of hacking that may have been going on at the tabloid. The paper's royal editor Clive Goodman and private investigator Glenn Mulcaire had both been jailed for hacking into phones of the royal household in 2007.